This study 15 to examine the warm/cool feeling and thermal transport properties of knitted fabrics for underwear, by means of Thermo Labo II type, measuring the qmax, thermal conductivity(λ) and surface property for ten kinds of knitted fabrics. And also, in order to confirm the validity of the qmax, to the maximum heat flux when a heat plate touches knitted fabrics under constant temperature, a sensory test were carried out by ten panels as an objective measure of warm/cool feeling. To the warm/cool feeling could be greatly affected by the moisture/air transport phenomena, to especially in underwear. And the moisture/air transport properties such as moisture transmittance and air permeability were measured by the evaporate method and the Frazier method, respectively. The experimental results were analyzed statistically to relate the thermal properties vs. moisture/air transport properties, relative humidity, and so on. The results of this study are as follows ; 1. The warm/cool feeling rating by sensory test has a degree of correlation with the qmax. And perception of knitted fabrics warm/cool feeling become dull when an environmental temperature is near to the skin temperature. When a skin under constant heat touches knitted fabrics, the qmax values of specimen materials are in the order of cotton>acrylic/cotton>cotton/acrylic> cotton/polyester>wool. Therefore, warm feeling of specimen materials are in the order of wool>cotton/polyester>cotton/acrylic> acrylic/cotton> cotton. 2.The qmax value increases along with the .relative humidity of environmental condition. Hence the cool feeling is recognized. Particularly, it is observed remarkably in cotton fibers, but not that much in wool fibers. And the warm/cool feeling of knitted fabrics for underwear shows that the larger the surface unevenness and the smaller bulk density, then the greater the warm feeling. 3.The qmax value of knitted fabrics for underwear has positive correlation with the transport properties such as the thermal transmittance(ic), the moisture transmittance(Mt) and the air permeability(Ap). The relation between the qmax and these properties is shown as the following equation. qmax(W/m$^2$) =3.2312 log(x) -2.5239 log(Mt) +0.106 log(Ap)